This invention relates to apparatus for measuring the distribution of tension in travelling flat workpieces, such as hot and cold sheets and strips of steel and aluminum and like metals as well as non-metallic materials, as they are being processed in rolling mills or in process lines. Also this invention is particularly useful for measuring the tension profile across a workpiece.
Flat workpieces such as steel and aluminum strip are rolled in commercial high capacity rolling mills employing highly automated processes in which mechanical properties and shape of the workpieces are closely monitored in order to maintain high product quality and mill utilization rates. Longitudinal tension variations are of particular concern because substantial variations affect the flatness of the workpieces. Thus, in such processes, the tension and/or other significant properties of travelling workpieces are measured, the measurements converted by tranducers to proportional signals which are fed to computing means such as microprocessors for controlling specific apparatus or to computers for controlling the entire mill or a portion of the mill.
Rolling mills, processes and apparatus in which the tension in a length of metal is measured are generally disclosed in the following U.S. Pat. Nos.: 3,817,095; 4,289,005; 4,332,154; 4,470,297; 4,561,313; 4,674,310 and 4,680,978, which disclosures are hereby incorporated by reference. U.S. Pat. Nos. 4,289,005 and 4,332,154 generally disclose tension measuring apparatus comprising roll segments adapted to engage the transverse width of travelling workpieces, which segments are rotatably mounted on bendable shafts. Roll segments are preferably used instead of rolls having continuous peripheral surfaces (as disclosed, e.g., in U.S. Pat. No. 4,470,297) because segmented rolls can detect tension variations across the transverse width of the workpiece. As is pointed out in U S. Pat. No. 4,561,313, however, segmented rolls may mark the surface of the workpieces engaged by the roll segments. The other patents generally disclose segments rolls comprising a series of rollers.